Dispersible amyloid β-protein oligomers, protofibrils, and fibrils represent diffusible but not soluble aggregates: Their role in neurodegeneration in amyloid precursor protein (APP) transgenic mice Academic Article uri icon

Overview

MeSH Major

  • Alzheimer Disease
  • Amyloid beta-Protein Precursor
  • Neurons
  • Plaque, Amyloid
  • Protein Multimerization
  • Synapses

abstract

  • Soluble amyloid β-protein (Aβ) aggregates have been identified in the Alzheimer's disease (AD) brain. Dispersed Aβ aggregates in the brain parenchyma are different from soluble, membrane-associated and plaque-associated solid aggregates. They are in mixture with the extra- or intracellular fluid but can be separated from soluble proteins by ultracentrifugation. To clarify the role of dispersible Aβ aggregates for neurodegeneration we analyzed 2 different amyloid precursor protein (APP)-transgenic mouse models. APP23 mice overexpress human mutant APP with the Swedish mutation. APP51/16 mice express high levels of human wild type APP. Both mice develop Aβ-plaques. Dendritic degeneration, neuron loss, and loss of asymmetric synapses were seen in APP23 but not in APP51/16 mice. The soluble and dispersible fractions not separated from one another were received as supernatant after centrifugation of native forebrain homogenates at 14,000 × g. Subsequent ultracentrifugation separated the soluble, i.e., the supernatant, from the dispersible fraction, i.e., the resuspended pellet. The major biochemical difference between APP23 and APP51/16 mice was that APP23 mice exhibited higher levels of dispersible Aβ oligomers, protofibrils and fibrils precipitated with oligomer (A11) and protofibril/fibril (B10AP) specific antibodies than APP51/16 mice. These differences, rather than soluble Aβ and Aβ plaque pathology were associated with dendritic degeneration, neuron, and synapse loss in APP23 mice in comparison with APP51/16 mice. Immunoprecipitation of dispersible Aβ oligomers, protofibrils, and fibrils revealed that they were associated with APP C-terminal fragments (APP-CTFs). These results indicate that dispersible Aβ oligomers, protofibrils, and fibrils represent an important pool of Aβ aggregates in the brain that critically interact with membrane-associated APP C-terminal fragments. The concentration of dispersible Aβ aggregates, thereby, presumably determines its toxicity.

publication date

  • November 2012

Research

keywords

  • Academic Article

Identity

Language

  • eng

Digital Object Identifier (DOI)

  • 10.1016/j.neurobiolaging.2011.12.032

PubMed ID

  • 22305478

Additional Document Info

start page

  • 2641

end page

  • 60

volume

  • 33

number

  • 11